package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Slf4j
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService seckillVoucherService;

    @Resource
    private RedisIdWorker redisIdWorker;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private RedissonClient redissonClient;

    //lua脚本
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static
    {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    //线程池
    private static final ExecutorService SECKILL_ORDER_EXECTOR = Executors.newSingleThreadExecutor();


    @PostConstruct
    private void init()
    {
        SECKILL_ORDER_EXECTOR.submit(new VoucherOrderHandler());
    }

    private class VoucherOrderHandler implements Runnable
    {
        //XGROUP CREATE stream.orders g1 0 MKSTREAM

        String queueName = "stream.orders";
        @Override
        public void run()
        {
            while (true)
            {
                try
                {
                    //1.获取消息队列中的订单信息
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queueName, ReadOffset.lastConsumed())
                    );

                    //2.判断消息获取是否成功
                    if(list == null || list.isEmpty())
                    {
                        //如果失败，说明没有消息，继续下一次循环
                        continue;
                    }

                    //3.获取消息成功，解析消息中的订单信息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);

                    //4.下单
                    handleVoucherOrder(voucherOrder);

                    //5.ACK确认
                    stringRedisTemplate.opsForStream().acknowledge(queueName,"g1",record.getId());
                }
                catch (Exception e)
                {
                    log.error("处理订单异常",e);
                    try {
                        handlePendingList();
                    } catch (InterruptedException ex) {
                        throw new RuntimeException(ex);
                    }
                }
            }
        }

        private void handlePendingList() throws InterruptedException {
            while (true)
            {
                try
                {
                    //1.获取pendingList中的订单信息
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(queueName, ReadOffset.from("0"))
                    );

                    //2.判断消息获取是否成功
                    if(list == null || list.isEmpty())
                    {
                        //如果失败，说明pendingList没有异常消息，结束循环
                        break;
                    }

                    //3.获取消息成功，解析消息中的订单信息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);

                    //4.下单
                    handleVoucherOrder(voucherOrder);

                    //5.ACK确认
                    stringRedisTemplate.opsForStream().acknowledge(queueName,"g1",record.getId());
                }
                catch (Exception e)
                {
                    log.error("处理pendingList订单异常",e);
                    Thread.sleep(20);
                }
            }
        }
    }

    /*
    //阻塞队列
    private BlockingQueue<VoucherOrder> orderTask = new ArrayBlockingQueue<>(1024 * 1024);
    private class VoucherOrderHandler implements Runnable
    {
        @Override
        public void run()
        {
            while (true)
            {
                try
                {
                    //1.获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTask.take();
                    //2.创建订单
                    handleVoucherOrder(voucherOrder);
                }
                catch (Exception e)
                {
                    log.error("处理订单异常",e);
                }
            }
        }
    }
     */

    private void handleVoucherOrder(VoucherOrder voucherOrder)
    {
        //1.获取用户
        Long userId = voucherOrder.getUserId();
        //2.创建锁对象
        //SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
        RLock lock = redissonClient.getLock("lock:order:" + userId);

        //3.获取锁
        boolean isLock = lock.tryLock();

        //4.判断是否获取锁成功
        if(!isLock)
        {
            //获取锁失败，返回错误或重试
            log.error("不允许重复下单");
            return;
        }

        try
        {

            proxy.createVoucherOrder(voucherOrder);
        }
        finally
        {
            //释放锁
            lock.unlock();
        }
    }

    private IVoucherOrderService proxy;

    @Override
    public Result seckillVoucher(Long voucherId)
    {
        Long userId = UserHolder.getUser().getId();
        long orderId = redisIdWorker.nextId("order");

        //1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString(),String.valueOf(orderId)
        );

        //2.判断结果是否为0
        int r = result.intValue();
        if( r != 0)
        {
            //2.1结果不为0，没有购买资格
            return Result.fail(r == 1 ? "库存不足！" : "不能重复下单！");
        }

        //获取代理对象(事务)  避免事务失效
        //获取当前类的代理对象（Proxy），并将其赋值给成员变量 proxy。
        proxy = (IVoucherOrderService) AopContext.currentProxy();

        //4.返回订单id
        return Result.ok(orderId);
    }

    /*
    @Override
    public Result seckillVoucher(Long voucherId)
    {
        Long userId = UserHolder.getUser().getId();

        //1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString()
        );

        //2.判断结果是否为0
        int r = result.intValue();
        if( r != 0)
        {
            //2.1结果不为0，没有购买资格
            return Result.fail(r == 1 ? "库存不足！" : "不能重复下单！");
        }
        //2.2结果为0，有资格下单，把下单信息保存到阻塞队列中
        //保存阻塞队列

        //3.创建订单
        VoucherOrder voucherOrder = new VoucherOrder();

        //3.1订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);

        //3.2用户id
        voucherOrder.setUserId(userId);

        //3.3代金券id
        voucherOrder.setVoucherId(voucherId);

        //3.4把订单信息放入阻塞队列中
        orderTask.add(voucherOrder);

        //获取代理对象(事务)  避免事务失效
        //获取当前类的代理对象（Proxy），并将其赋值给成员变量 proxy。
        proxy = (IVoucherOrderService) AopContext.currentProxy();

        //4.返回订单id
        return Result.ok(orderId);
    }
     */

    /*
    @Override
    public Result seckillVoucher(Long voucherId)
    {
        //1.查询优惠劵
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);

        //2.判断秒杀是否开始
        if(voucher.getBeginTime().isAfter(LocalDateTime.now()))
        {
            //尚未开始
            return Result.fail("秒杀尚未开始!");
        }

        //3.判断秒杀是否结束
        if(voucher.getEndTime().isBefore(LocalDateTime.now()))
        {
            //已经结束
            return Result.fail("秒杀已经结束!");
        }

        //4.判断库存是否充足
        if(voucher.getStock() < 1)
        {
            //库存不足
            return Result.fail("库存不足!");
        }

        Long userId = UserHolder.getUser().getId();

        //创建锁对象
        //SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
        RLock lock = redissonClient.getLock("lock:order:" + userId);

        //获取锁
        boolean isLock = lock.tryLock();

        //判断是否获取锁成功
        if(!isLock)
        {
            //获取锁失败，返回错误或重试
            return Result.fail("不允许重复下单!");
        }


        try
        {
            //获取代理对象(事务)
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVoucherOrder(voucherId);
        }
        finally
        {
            //释放锁
            lock.unlock();
        }

    }
     */

    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder)
    {
        //5.一人一单
        Long userId = voucherOrder.getUserId();
        //5.1查询订单
        int count = query().eq("user_id",userId).eq("voucher_id", voucherOrder.getVoucherId()).count();

        //5.2判断是否已经存在
        if(count > 0)
        {
            //用户已经购买过了
            log.error("用户已经购买过一次了!");
            return;
        }

        //6.扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")
                .eq("voucher_id", voucherOrder.getVoucherId()).gt("stock", 0)  //where id = ? and stock > 0
                .update();
        if(!success)
        {
            //扣减失败
            log.error("库存不足!");
            return;
        }

        save(voucherOrder);
    }

}
